Toner and production method thereof, image forming apparatus and image forming method, and process cartridge

Abstract

The object of the invention is to provide a toner enabling excellent transferring properties, cleanability, and fixability and forming a high-precision image without substantially degraded image quality even after printed on a number of sheets of paper. The invention also provides the toner-production method, an image forming apparatus, an image forming method, and a process cartridge. To this end, the present invention provides a toner which comprises toner-base particles containing a binder resin and a filler, and inorganic fine particles, in which the filler is included in a filler-layer in the vicinity of surfaces of the toner-base particles, the number average particle diameter of the primary particles of the inorganic fine particles is 90 nm to 300 nm, and the average circularity of the toner is 0.95.

1. A toner comprising:
 a binder resin; 
 toner-base particles containing an inorganic filler, and 
 inorganic fine particles, 
 wherein the toner is obtained by adding, into an aqueous medium, a toner material liquid in which at least the binder resin and the inorganic filler are dispersed and/or dissolved in an organic solvent, so that the toner material liquid is emulsified, and removing the organic solvent therefrom, 
 wherein the filler is contained in a filler-layer in the vicinity of a surface of the toner-base particles, a number average particle diameter of the primary particles of the inorganic fine particles is 90 nm to 300 nm, and the average circularity of the toner is 0.94 or more, and 
 wherein a filler-existence ratio X surf  of the filler which exists in a region from the surface to a depth of 200 nm from the surface of the toner base particles and an average filler-existence ratio X total  of the filler present in a total content of the toner base particles satisfy an inequality of X surf >X total . 
 
     
     
       2. The toner according to  claim 1 , wherein a part of the filler exists in a state being exposed on a surface of the toner. 
     
     
       3. The toner according to  claim 1 , wherein a content of the filler in the toner is 0.01% by mass to 20% by mass. 
     
     
       4. The toner according to  claim 1 , wherein a ratio of a volume average particle diameter of the primary particles of the filler to a volume average particle diameter of the toner is 0.1 or less. 
     
     
       5. The toner according to  claim 1 , wherein a volume average particle diameter of the primary particles of the filler is 0.001 μm to 0.5 μm. 
     
     
       6. The toner according to  claim 1 , wherein the inorganic filler comprises one selected from the group consisting of metallic oxides, metallic hydroxides, metallic carboxylates, metallic sulfate, metallic silicates, metallic nitrides, metallic phosphates, metallic borates, metallic titanates, metallic sulfides, and carbons. 
     
     
       7. The toner according to  claim 1 , wherein the filler comprises any one of silica, alumina, and titania. 
     
     
       8. The toner according to  claim 7 , wherein the filler comprises a silica, having a silicon content of a surface of the silica according to X-ray photoemission spectroscopy is 0.5 atomic % to 10 atomic %. 
     
     
       9. The toner according to  claim 1 , wherein the surface of the filler is subjected to a surface treatment with at least one selected from the group consisting of silane coupling agents, titanate coupling agents, alminate coupling agents, and tertiary amine compounds. 
     
     
       10. The toner according to  claim 1 , wherein the filler has a hydrophobicization degree of 15% to 55%. 
     
     
       11. The toner according to  claim 1 , wherein the inorganic fine particles comprise a silica formed in a spherical shape. 
     
     
       12. The toner according to  claim 1 , wherein the inorganic fine particles are produced by a sol-gel process. 
     
     
       13. The toner according to  claim 1 , wherein the toner is obtained by dispersing the toner in an aqueous medium in which the dispersed toner is subjected to a surface treatment with a fluorine-containing quaternary ammonium salt. 
     
     
       14. The toner according to  claim 13 , wherein the toner has a fluorine atom content of the fluorine-containing compound being from 2.0 atomic % to 15 atomic % according to X-ray photoemission spectroscopy. 
     
     
       15. The toner according to  claim 1 , wherein a charge-controlling agent is externally added to the toner-base particles. 
     
     
       16. The toner according to  claim 15 , wherein the charge-controlling agent is externally added to the toner-base particles by a wet process. 
     
     
       17. The toner according to  claim 1  further comprising a wax. 
     
     
       18. The toner according to  claim 1 , wherein the binder resin comprises a modified polyester (i). 
     
     
       19. The toner according to  claim 18 , wherein the toner comprises an unmodified polyester (ii) as well as the modified polyester (i) and has a mass ratio of the modified polyester to the unmodified polyester is 5/95 to 80/20. 
     
     
       20. The toner according to  claim 1 , wherein the toner-base particles are produced by
 dispersing and dissolving toner materials comprising a polyester prepolymer having at least a functional group containing a nitrogen atom, a polyester, and a filler in an organic solvent, and further dispersing the toner materials in an aqueous medium, and 
 subjecting at least the polyester prepolymer to a cross-linking and/or an elongation reaction. 
 
     
     
       21. The toner according to  claim 1 , wherein the toner has a shape factor SF-1 of 110 to 140, a shape factor SF-2 of 120 to 160, and a ratio Dv/Dn of a volume average particle diameter (Dv) to a number average particle diameter (Dn) being 1.01 to 1.40. 
     
     
       22. The toner according to  claim 1 , wherein the toner is a full-color image-forming toner used for an image-forming apparatus, in which color-images formed on a latent image carrier are sequentially transferred onto an intermediate transferring member and then transferred onto a recording medium in block to fix the color images and to form a full-color image. 
     
     
       23. A developer for developing a latent electrostatic image formed on a latent image carrier,
 wherein the developer is a two-component developer which comprises a toner and carrier; and the toner comprises at least a binder resin, toner-base particles containing an inorganic filler, and inorganic fine particles; 
 wherein the toner is obtained by adding, into an aqueous medium, a toner material liquid in which at least the binder resin and the inorganic filler are dispersed and/or dissolved in an organic solvent, so that the toner material liquid is emulsified, and removing the organic solvent therefrom, 
 wherein the filler is contained in a filler-layer in the vicinity of a surface of the toner-base particles, a number average particle diameter of the primary particles of the inorganic fine particles is 90 nm to 300 nm, and the average circularity of the toner is 0.94 or more; and 
 wherein a filler-existence ratio X surf  of the filler which exists in a region from the surface to a depth of 200 nm from the surface of the toner base particles and an average filler-existence ratio X total  of the filler present in a total content of the toner base particles satisfy an inequality of X surf >X total . 
 
     
     
       24. A process cartridge comprising:
 a latent image carrier, and 
 a developing unit, 
 wherein the latent image carrier is configured to carry a latent image, the developing unit is configured to develop the latent electrostatic image formed on the surface of the latent image carrier into a visible image by supplying a toner to the latent electrostatic image, and the latent image carrier and the developing unit are formed in a singled body and detachably mounted to the main body of an image-forming apparatus, and 
 wherein the toner comprises at least a binder resin, toner-base particles containing an inorganic filler, and inorganic fine particles; 
 wherein the toner is obtained by adding, into an aqueous medium, a toner material liquid in which at least the binder resin and the inorganic filler are dispersed and/or dissolved in an organic solvent, so that the toner material liquid is emulsified, and removing the organic solvent therefrom, 
 wherein the filler is contained in a filler-layer in the vicinity of a surface of the toner-base particles, a number average particle diameter of the primary particles of the inorganic fine particles is 90 nm to 300 nm, and the average circularity of the toner is 0.94 or more; and 
 wherein a filler-existence ratio X surf  of the filler which exists in a region from the surface to a depth of 200 nm from the surface of the toner base particles and an average filler-existence ratio X total  of the filler present in a total content of the toner base particles satisfy an inequality of X surf >X total . 
 
     
     
       25. An image-forming apparatus comprising:
 a latent image carrier configured to carry a latent image, 
 a charging unit configured to uniformly charge a surface of the latent image carrier, 
 an exposing unit configured to expose the charged surface of the latent image carrier based on image data to form a latent electrostatic image on the latent image carrier, 
 a developing unit configured to develop the latent electrostatic image formed on the surface of the latent image carrier into a visible image by supplying a toner to the latent electrostatic image, 
 a transferring unit configured to transfer the visible image on the surface of the latent image carrier to a recording medium, and 
 a fixing unit configured to fix the visible image on the recording medium, 
 wherein the toner comprises at least a binder resin, toner-base particles containing an inorganic filler, and inorganic fine particles; 
 wherein the toner is obtained by adding, into an aqueous medium, a toner material liquid in which at least the binder resin and the inorganic filler are dispersed and/or dissolved in an organic solvent, so that the toner material liquid is emulsified, and removing the organic solvent therefrom, 
 wherein the filler is contained in a filler-layer in the vicinity of a surface of the toner-base particles, a number average particle diameter of the primary particles of the inorganic fine particles is 90 nm to 300 nm, and the average circularity of the toner is 0.94 or more; and 
 wherein a filler-existence ratio X surf  of the filler which exists in a region from the surface to a depth of 200 nm from the surface of the toner base particles and an average filler-existence ratio X total  of the filler present in a total content of the toner base particles satisfy an inequality of X surf >X total . 
 
     
     
       26. An image-forming method comprising:
 charging a surface of a latent image carrier uniformly, 
 exposing the charged surface of the latent image carrier based on image data to form a latent electrostatic image on the latent image carrier, 
 developing the latent electrostatic image formed on the surface of the latent image carrier into a visible image by supplying a toner to the latent electrostatic image, 
 transferring the visible image on the surface of the latent image carrier to a recording medium, and 
 fixing the visible image on the recording medium, 
 wherein the toner comprises at least a binder resin, toner-base particles containing an inorganic filler, and inorganic fine particles; 
 wherein the toner is obtained by adding, into an aqueous medium, a toner material liquid in which at least the binder resin and the inorganic filler are dispersed and/or dissolved in an organic solvent, so that the toner material liquid is emulsified, and removing the organic solvent therefrom, 
 wherein the filler is contained in a filler-layer in the vicinity of a surface of the toner-base particles, a number average particle diameter of the primary particles of the inorganic fine particles is 90 nm to 300 nm, and the average circularity of the toner is 0.94 or more; and 
 wherein a filler-existence ratio X surf  of the filler which exists in a region from the surface to a depth of 200 nm from the surface of the toner base particles and an average filler-existence ratio X total  of the filler present in a total content of the toner base particles satisfy an inequality of X surf >X total . 
 
     
     
       27. The toner according to  claim 1 , wherein the filler is added, as an organosol in a dispersed state, into the toner material liquid. 
     
     
       28. The toner according to  claim 1 , wherein assuming that a total projected area of the toner is represented as S, and a total area of portions of the toner in contact with a latent image bearing member is represented as A, a ratio of A/S of the total area A to the total projected area of the toner S is 15% to 40%.